remove leak_check from the outlives predicate evaluations

Author: nikomatsakis

src/librustc_infer/infer/mod.rs

@@ -991,14 +991,12 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
             return None;
         }
 
-        Some(self.commit_if_ok(|snapshot| {
+        Some(self.commit_if_ok(|_snapshot| {
             let (ty::SubtypePredicate { a_is_expected, a, b }, _) =
                 self.replace_bound_vars_with_placeholders(&predicate);
 
             let ok = self.at(cause, param_env).sub_exp(a_is_expected, a, b)?;
 
-            self.leak_check(false, snapshot)?;
-
             Ok(ok.unit())
         }))
     }
@@ -1008,14 +1006,13 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
         cause: &traits::ObligationCause<'tcx>,
         predicate: ty::PolyRegionOutlivesPredicate<'tcx>,
     ) -> UnitResult<'tcx> {
-        self.commit_if_ok(|snapshot| {
+        self.commit_if_ok(|_snapshot| {
             let (ty::OutlivesPredicate(r_a, r_b), _) =
                 self.replace_bound_vars_with_placeholders(&predicate);
             let origin = SubregionOrigin::from_obligation_cause(cause, || {
                 RelateRegionParamBound(cause.span)
             });
             self.sub_regions(origin, r_b, r_a); // `b : a` ==> `a <= b`
-            self.leak_check(false, snapshot)?;
             Ok(())
         })
     }